summaryrefslogtreecommitdiffstats
path: root/drivers/clk/samsung/clk-cpu.c
blob: 813003d6ce097f4bbbda48e7d471b73388b611ac (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
/*
 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
 * Author: Thomas Abraham <thomas.ab@samsung.com>
 *
 * Copyright (c) 2015 Samsung Electronics Co., Ltd.
 * Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This file contains the utility function to register CPU clock for Samsung
 * Exynos platforms. A CPU clock is defined as a clock supplied to a CPU or a
 * group of CPUs. The CPU clock is typically derived from a hierarchy of clock
 * blocks which includes mux and divider blocks. There are a number of other
 * auxiliary clocks supplied to the CPU domain such as the debug blocks and AXI
 * clock for CPU domain. The rates of these auxiliary clocks are related to the
 * CPU clock rate and this relation is usually specified in the hardware manual
 * of the SoC or supplied after the SoC characterization.
 *
 * The below implementation of the CPU clock allows the rate changes of the CPU
 * clock and the corresponding rate changes of the auxillary clocks of the CPU
 * domain. The platform clock driver provides a clock register configuration
 * for each configurable rate which is then used to program the clock hardware
 * registers to acheive a fast co-oridinated rate change for all the CPU domain
 * clocks.
 *
 * On a rate change request for the CPU clock, the rate change is propagated
 * upto the PLL supplying the clock to the CPU domain clock blocks. While the
 * CPU domain PLL is reconfigured, the CPU domain clocks are driven using an
 * alternate clock source. If required, the alternate clock source is divided
 * down in order to keep the output clock rate within the previous OPP limits.
*/

#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include "clk-cpu.h"

#define E4210_SRC_CPU		0x0
#define E4210_STAT_CPU		0x200
#define E4210_DIV_CPU0		0x300
#define E4210_DIV_CPU1		0x304
#define E4210_DIV_STAT_CPU0	0x400
#define E4210_DIV_STAT_CPU1	0x404

#define E4210_DIV0_RATIO0_MASK	0x7
#define E4210_DIV1_HPM_MASK	(0x7 << 4)
#define E4210_DIV1_COPY_MASK	(0x7 << 0)
#define E4210_MUX_HPM_MASK	(1 << 20)
#define E4210_DIV0_ATB_SHIFT	16
#define E4210_DIV0_ATB_MASK	(DIV_MASK << E4210_DIV0_ATB_SHIFT)

#define MAX_DIV			8
#define DIV_MASK		7
#define DIV_MASK_ALL		0xffffffff
#define MUX_MASK		7

/*
 * Helper function to wait until divider(s) have stabilized after the divider
 * value has changed.
 */
static void wait_until_divider_stable(void __iomem *div_reg, unsigned long mask)
{
	unsigned long timeout = jiffies + msecs_to_jiffies(10);

	do {
		if (!(readl(div_reg) & mask))
			return;
	} while (time_before(jiffies, timeout));

	if (!(readl(div_reg) & mask))
		return;

	pr_err("%s: timeout in divider stablization\n", __func__);
}

/*
 * Helper function to wait until mux has stabilized after the mux selection
 * value was changed.
 */
static void wait_until_mux_stable(void __iomem *mux_reg, u32 mux_pos,
					unsigned long mux_value)
{
	unsigned long timeout = jiffies + msecs_to_jiffies(10);

	do {
		if (((readl(mux_reg) >> mux_pos) & MUX_MASK) == mux_value)
			return;
	} while (time_before(jiffies, timeout));

	if (((readl(mux_reg) >> mux_pos) & MUX_MASK) == mux_value)
		return;

	pr_err("%s: re-parenting mux timed-out\n", __func__);
}

/* common round rate callback useable for all types of CPU clocks */
static long exynos_cpuclk_round_rate(struct clk_hw *hw,
			unsigned long drate, unsigned long *prate)
{
	struct clk_hw *parent = clk_hw_get_parent(hw);
	*prate = clk_hw_round_rate(parent, drate);
	return *prate;
}

/* common recalc rate callback useable for all types of CPU clocks */
static unsigned long exynos_cpuclk_recalc_rate(struct clk_hw *hw,
			unsigned long parent_rate)
{
	/*
	 * The CPU clock output (armclk) rate is the same as its parent
	 * rate. Although there exist certain dividers inside the CPU
	 * clock block that could be used to divide the parent clock,
	 * the driver does not make use of them currently, except during
	 * frequency transitions.
	 */
	return parent_rate;
}

static const struct clk_ops exynos_cpuclk_clk_ops = {
	.recalc_rate = exynos_cpuclk_recalc_rate,
	.round_rate = exynos_cpuclk_round_rate,
};

/*
 * Helper function to set the 'safe' dividers for the CPU clock. The parameters
 * div and mask contain the divider value and the register bit mask of the
 * dividers to be programmed.
 */
static void exynos_set_safe_div(void __iomem *base, unsigned long div,
					unsigned long mask)
{
	unsigned long div0;

	div0 = readl(base + E4210_DIV_CPU0);
	div0 = (div0 & ~mask) | (div & mask);
	writel(div0, base + E4210_DIV_CPU0);
	wait_until_divider_stable(base + E4210_DIV_STAT_CPU0, mask);
}

/* handler for pre-rate change notification from parent clock */
static int exynos_cpuclk_pre_rate_change(struct clk_notifier_data *ndata,
			struct exynos_cpuclk *cpuclk, void __iomem *base)
{
	const struct exynos_cpuclk_cfg_data *cfg_data = cpuclk->cfg;
	unsigned long alt_prate = clk_get_rate(cpuclk->alt_parent);
	unsigned long alt_div = 0, alt_div_mask = DIV_MASK;
	unsigned long div0, div1 = 0, mux_reg;
	unsigned long flags;

	/* find out the divider values to use for clock data */
	while ((cfg_data->prate * 1000) != ndata->new_rate) {
		if (cfg_data->prate == 0)
			return -EINVAL;
		cfg_data++;
	}

	spin_lock_irqsave(cpuclk->lock, flags);

	/*
	 * For the selected PLL clock frequency, get the pre-defined divider
	 * values. If the clock for sclk_hpm is not sourced from apll, then
	 * the values for DIV_COPY and DIV_HPM dividers need not be set.
	 */
	div0 = cfg_data->div0;
	if (cpuclk->flags & CLK_CPU_HAS_DIV1) {
		div1 = cfg_data->div1;
		if (readl(base + E4210_SRC_CPU) & E4210_MUX_HPM_MASK)
			div1 = readl(base + E4210_DIV_CPU1) &
				(E4210_DIV1_HPM_MASK | E4210_DIV1_COPY_MASK);
	}

	/*
	 * If the old parent clock speed is less than the clock speed of
	 * the alternate parent, then it should be ensured that at no point
	 * the armclk speed is more than the old_prate until the dividers are
	 * set.  Also workaround the issue of the dividers being set to lower
	 * values before the parent clock speed is set to new lower speed
	 * (this can result in too high speed of armclk output clocks).
	 */
	if (alt_prate > ndata->old_rate || ndata->old_rate > ndata->new_rate) {
		unsigned long tmp_rate = min(ndata->old_rate, ndata->new_rate);

		alt_div = DIV_ROUND_UP(alt_prate, tmp_rate) - 1;
		WARN_ON(alt_div >= MAX_DIV);

		if (cpuclk->flags & CLK_CPU_NEEDS_DEBUG_ALT_DIV) {
			/*
			 * In Exynos4210, ATB clock parent is also mout_core. So
			 * ATB clock also needs to be mantained at safe speed.
			 */
			alt_div |= E4210_DIV0_ATB_MASK;
			alt_div_mask |= E4210_DIV0_ATB_MASK;
		}
		exynos_set_safe_div(base, alt_div, alt_div_mask);
		div0 |= alt_div;
	}

	/* select sclk_mpll as the alternate parent */
	mux_reg = readl(base + E4210_SRC_CPU);
	writel(mux_reg | (1 << 16), base + E4210_SRC_CPU);
	wait_until_mux_stable(base + E4210_STAT_CPU, 16, 2);

	/* alternate parent is active now. set the dividers */
	writel(div0, base + E4210_DIV_CPU0);
	wait_until_divider_stable(base + E4210_DIV_STAT_CPU0, DIV_MASK_ALL);

	if (cpuclk->flags & CLK_CPU_HAS_DIV1) {
		writel(div1, base + E4210_DIV_CPU1);
		wait_until_divider_stable(base + E4210_DIV_STAT_CPU1,
				DIV_MASK_ALL);
	}

	spin_unlock_irqrestore(cpuclk->lock, flags);
	return 0;
}

/* handler for post-rate change notification from parent clock */
static int exynos_cpuclk_post_rate_change(struct clk_notifier_data *ndata,
			struct exynos_cpuclk *cpuclk, void __iomem *base)
{
	const struct exynos_cpuclk_cfg_data *cfg_data = cpuclk->cfg;
	unsigned long div = 0, div_mask = DIV_MASK;
	unsigned long mux_reg;
	unsigned long flags;

	/* find out the divider values to use for clock data */
	if (cpuclk->flags & CLK_CPU_NEEDS_DEBUG_ALT_DIV) {
		while ((cfg_data->prate * 1000) != ndata->new_rate) {
			if (cfg_data->prate == 0)
				return -EINVAL;
			cfg_data++;
		}
	}

	spin_lock_irqsave(cpuclk->lock, flags);

	/* select mout_apll as the alternate parent */
	mux_reg = readl(base + E4210_SRC_CPU);
	writel(mux_reg & ~(1 << 16), base + E4210_SRC_CPU);
	wait_until_mux_stable(base + E4210_STAT_CPU, 16, 1);

	if (cpuclk->flags & CLK_CPU_NEEDS_DEBUG_ALT_DIV) {
		div |= (cfg_data->div0 & E4210_DIV0_ATB_MASK);
		div_mask |= E4210_DIV0_ATB_MASK;
	}

	exynos_set_safe_div(base, div, div_mask);
	spin_unlock_irqrestore(cpuclk->lock, flags);
	return 0;
}

/*
 * This notifier function is called for the pre-rate and post-rate change
 * notifications of the parent clock of cpuclk.
 */
static int exynos_cpuclk_notifier_cb(struct notifier_block *nb,
				unsigned long event, void *data)
{
	struct clk_notifier_data *ndata = data;
	struct exynos_cpuclk *cpuclk;
	void __iomem *base;
	int err = 0;

	cpuclk = container_of(nb, struct exynos_cpuclk, clk_nb);
	base = cpuclk->ctrl_base;

	if (event == PRE_RATE_CHANGE)
		err = exynos_cpuclk_pre_rate_change(ndata, cpuclk, base);
	else if (event == POST_RATE_CHANGE)
		err = exynos_cpuclk_post_rate_change(ndata, cpuclk, base);

	return notifier_from_errno(err);
}

/* helper function to register a CPU clock */
int __init exynos_register_cpu_clock(struct samsung_clk_provider *ctx,
		unsigned int lookup_id, const char *name, const char *parent,
		const char *alt_parent, unsigned long offset,
		const struct exynos_cpuclk_cfg_data *cfg,
		unsigned long num_cfgs, unsigned long flags)
{
	struct exynos_cpuclk *cpuclk;
	struct clk_init_data init;
	struct clk *clk;
	int ret = 0;

	cpuclk = kzalloc(sizeof(*cpuclk), GFP_KERNEL);
	if (!cpuclk)
		return -ENOMEM;

	init.name = name;
	init.flags = CLK_SET_RATE_PARENT;
	init.parent_names = &parent;
	init.num_parents = 1;
	init.ops = &exynos_cpuclk_clk_ops;

	cpuclk->hw.init = &init;
	cpuclk->ctrl_base = ctx->reg_base + offset;
	cpuclk->lock = &ctx->lock;
	cpuclk->flags = flags;
	cpuclk->clk_nb.notifier_call = exynos_cpuclk_notifier_cb;

	cpuclk->alt_parent = __clk_lookup(alt_parent);
	if (!cpuclk->alt_parent) {
		pr_err("%s: could not lookup alternate parent %s\n",
				__func__, alt_parent);
		ret = -EINVAL;
		goto free_cpuclk;
	}

	clk = __clk_lookup(parent);
	if (!clk) {
		pr_err("%s: could not lookup parent clock %s\n",
				__func__, parent);
		ret = -EINVAL;
		goto free_cpuclk;
	}

	ret = clk_notifier_register(clk, &cpuclk->clk_nb);
	if (ret) {
		pr_err("%s: failed to register clock notifier for %s\n",
				__func__, name);
		goto free_cpuclk;
	}

	cpuclk->cfg = kmemdup(cfg, sizeof(*cfg) * num_cfgs, GFP_KERNEL);
	if (!cpuclk->cfg) {
		pr_err("%s: could not allocate memory for cpuclk data\n",
				__func__);
		ret = -ENOMEM;
		goto unregister_clk_nb;
	}

	clk = clk_register(NULL, &cpuclk->hw);
	if (IS_ERR(clk)) {
		pr_err("%s: could not register cpuclk %s\n", __func__,	name);
		ret = PTR_ERR(clk);
		goto free_cpuclk_data;
	}

	samsung_clk_add_lookup(ctx, clk, lookup_id);
	return 0;

free_cpuclk_data:
	kfree(cpuclk->cfg);
unregister_clk_nb:
	clk_notifier_unregister(__clk_lookup(parent), &cpuclk->clk_nb);
free_cpuclk:
	kfree(cpuclk);
	return ret;
}